deps: Downgrade google-http-client to v1.47.1 and google-api-java-client to v2.8.0 (#28713)

* deps: Downgrade google-http-client to v1.47.1

* chore: Downgrade google-api-client to v2.8.0

Author: lqiu96

generator/src/googleapis/codegen/languages/java/2.0.0/features.json

@@ -3,10 +3,10 @@
   "description": "Java libraries for Google APIs.",
   "generator": "java1_15",
   "releaseVersion": "2.0.0",
-  "baseClientLibrary": "2.8.1",
+  "baseClientLibrary": "2.8.0",
   "oauthClientLibrary": "1.39.0",
   "gsonVersion": "2.11.0",
-  "httpClientLibrary": "2.0.0",
+  "httpClientLibrary": "1.47.1",
   "httpClientVersion": "4.5.14",
   "jackson2CoreVersion": "2.19.0",
   "jdo2ApiVersion": "2.3-eb",